Peltigera britannica and P. leucophlebia
A few years ago, Sheila Street introduced the Highland Biological Recording Group to the lichens in the genus Peltigera, which contains the dog-lichens. Some of these are very common in Highland, especially P. membranacea and P. lactucifolia. The two that are particularly intriguing are two bright green species with cephalodia (nodules containing cyanobacterial photobionts in addition to the green algae in the main thallus): the rare P. britannica and rather more widespread P. leucophlebia. Both species occur widely in Highland, sometimes close together, but are both very scarce. See maps of P. britannica and P. leucophlebia on the NBN Gateway.
| Peltigera britannica | Peltigera leucophlebia |
 Peltigera britannica at Knockfarrel.The black cephalodia are clearly visible against the bright green thallus. Photo © Murdo Macdonald. |
 Peltigera leucophlebia at Orrin Falls.The similarity of the two species is obvious. The apparent difference in shade of green is not significant. Photo © Murdo Macdonald. |
 Habitat of Peltigera britannica on an exposed, north-facing outcrop of Old Red Sandstone conglomerate at Knockfarrel. This is a dry site. Much of the face is covered by the inland form of Ramalina siliquosa. (Previously this had been thought to be R. cuspidata, but that has been corrected by Brian Coppins.) Photo © Murdo Macdonald. | Identification: These lichens are easily recognised as a pair from the bright green leafy lobes, and the black dots of the cephalodia scattered over the surface. When dry they are grey or brownish. Separating the two species is more difficult. P. leucophlebia has obvious contrasting dark veins, and the cephalodia in the dry thallus (which is greyish, not green) are firmly attached (use the tip of a mounted needle). The veins of P. britannica are indistinct, pale, and the cephalodia detach easily from the dry thallus. The sites I have found have varied from exposed dry places to shady and humid, so they may be looked for anywhere. P. leucophlebia reputedly prefers more basic habitats than britannica, though that is not obvious in the mid-Ross sites. The two species were once confused, and were previously known as P. aphthosa, a species which is not known to occur in Britain Records of these rare lichens can be reported initially by email giving date, place, six-figure grid reference and any other relevant details. Details of how to submit a specimen for confirmation will then be provided. |
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